Dynamic characteristics from single-vortex stage to three-vortex one in case 2. Panels (a1)–(a4): Plumes 1–3 are pointed out by the cyan, red, and green arrows, respectively. The yellow arrows in panel (a2) indicate the velocity fields of the single vortex. Panels (b1)–(b4): Bright upflow is pointed out by magenta arrows. The yellow arrows in panel (b3) indicate the velocity fields of the three vortices. An animation of NVST Hα observations from 6 September 2023 at 01:42:24 UT to 02:29:56 UT, showing the evolutions of the plumes, the bright upflow and the single vortex splitting into three vortices, is available online. The real-time duration of this animation is 6 s.